Four examples of the Uniformity illusion with a conjunction of shape and luminance as an example. 
  • Open the video fullscreen.
  • Keep your eyes fixated on the centre of the screen for a good amount of time (tens of seconds to minutes).
  • The first two examples contain no fixation spot, the latter two are identical to the first two, but they do contain a fixation spot. Some people find that the illusion works better without a fixation spot, but you can try out which works best for yourself. 
For more information, see the text below the examples.

More information: The peripheral stimuli are white circles, the central are dark grey circles. The luminance of the central circles spreads out to the periphery. However, only other circles are affected, the rest of the periphery is unchanged. This is clear in the first example, but more dramatically shown in the second. This shows that features do not spread out 'blindly', but they are bound to specific other features. In this case luminance is spread out in conjunction with shape. Dark grey spreads out, but only to other circles.